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NAME

       strdup, strndup, strdupa, strndupa - duplicate a string

SYNOPSIS

       #include <string.h>

       char *strdup(const char *s);

       char *strndup(const char *s, size_t n);
       char *strdupa(const char *s);
       char *strndupa(const char *s, size_t n);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       strdup():
           _XOPEN_SOURCE >= 500
               || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       strndup():
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE
       strdupa(), strndupa(): _GNU_SOURCE

DESCRIPTION

       The strdup() function returns a pointer to a new string which is a duplicate of the string
       s.  Memory for the new string is obtained with malloc(3), and can be freed with free(3).

       The strndup() function is similar, but copies at most n bytes.  If s  is  longer  than  n,
       only n bytes are copied, and a terminating null byte ('\0') is added.

       strdupa()  and strndupa() are similar, but use alloca(3) to allocate the buffer.  They are
       available only when using the  GNU  GCC  suite,  and  suffer  from  the  same  limitations
       described in alloca(3).

RETURN VALUE

       On  success, the strdup() function returns a pointer to the duplicated string.  It returns
       NULL if insufficient memory was available, with errno set to indicate  the  cause  of  the
       error.

ERRORS

       ENOMEM Insufficient memory available to allocate duplicate string.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────────┬───────────────┬─────────┐
       │InterfaceAttributeValue   │
       ├────────────────────────────────┼───────────────┼─────────┤
       │strdup(), strndup(), strdupa(), │ Thread safety │ MT-Safe │
       │strndupa()                      │               │         │
       └────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       strdup()  conforms  to  SVr4,  4.3BSD,  POSIX.1-2001.  strndup() conforms to POSIX.1-2008.
       strdupa() and strndupa() are GNU extensions.

SEE ALSO

       alloca(3), calloc(3), free(3), malloc(3), realloc(3), string(3), wcsdup(3)

COLOPHON

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       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.